1. Technical Field
The present invention relates to wireless transmission systems and, more particularly, to the conveyance of control information in such systems.
2. Description of the Related Art
In broadband wireless systems, such as Orthogonal Frequency Division Multiple Access (OFDMA) based systems, control information regarding transmitted data streams in the downlink to a mobile user is signaled implicitly via a control channel by a base station in the system. The parameters specified in this information can considerably affect the rate of the transmission and the decoding accuracy. For example, for the Long Term Evolution (LTE)-Advanced standard, one proposal signals the total number of streams, the allocation of stream identifiers to a particular user, and the modulation type utilized by other co-scheduled multiple input-multiple output (MIMO) users in a Multiuser (MU)-MIMO transmission. Here, the control signals are designed by considering all the feed-forward control parameters jointly. For example, for a feed-forward sequence having a length of five bits, the 2^5=32 different possible indices are divided into different sets that are allocated to support 2 stream, 4 stream and 8 stream transmission, respectively.